Oral squamous carcinoma is among the top ten most frequently occurring cancers in the world. The overall five year prognosis for patients with oral malignancies is about 50 percent, which is lower than the comparable squamous carcinoma of the cervix. The incidence of both cervical and oral carcinomas increase when associated with two prominent risk factors, cigarette smoking and alcohol consumption. In addition, cervical cancer is strongly correlated with HPV infection. Ninety percent of cervical cancer harbor "high-risk" serotype of HPV genome. On the other hand, data on the causal relationship between oral cancer and HPV infection have been variable. In spite of the similarities in the role of HPV in the development of cancer in the oral and genital mucosa, there are also significant differences in the cellular and the environmental properties of the two types of mucosa. This will likely result in differences in the pathways of cancer development. To investigate the differential expression of the genes as cells transforms to tumor, we will utilize an in vitro model system developed by Park et al. In this model, normal oral keratinocytes are infected with HPV to become immortalized cells. Then the cells are exposed to a tobacco-related carcinogen, which converts the cells to a tumor. Using this model system, we will isolate and characterize differentially expressed gene(s) by the mRNA differential display (mRNA DD) analysis, as the cells progress to the malignant phenotype. We will then confirm the mRNA DD analysis by the Northern analysis to observe the expression pattern and the stability of expression in various established cell lines and primary cultures. In addition, RT-PCR and in situ hybridization will be performed with patient biopsies to determine the cell type and the stage specificity of the isolated mRNA DD products. The up-or down-regulated cDNA clones obtained from the mRNA DD analysis will be used for either expression or direct cloning to study its function in conferring HPV-mediated carcinogenesis. This project may eventually identify specific biomarkers that are consistently present in certain stages of neoplastic conversion. A quick diagnostic method can then be developed to screen patients routinely by a sensitive, cost-effective procedure. Early detection can be provided during normal office visits to increase the chance of survival from oral cancer.